In customer add page

### Description of issue
Customer name missing description of format and phone number too
Id number validation error it accepts special character and email input error also

```
Path: /pages/customer/addcustomer.html
Browser: Chrome 112.0.0.0 on Windows 10
Viewport: 1504 x 892 @1.5x
Language: en-GB
Cookies: Enabled
```

[Open in BrowserStack](https://www.browserstack.com/user/try-live?url=https%3A%2F%2Fdeploy-preview-1--mam-billing.netlify.app%2Fpages%2Fcustomer%2Faddcustomer.html&os=Windows&os_version=10&browser=Chrome&browser_version=112.0&resolution=1504x892&speed=1&start=true&ref=netlify-source)

Submitted from [Netlify Deploy Preview #1](https://deploy-preview-1--mam-billing.netlify.app/pages/customer/addcustomer.html)

Start with /pages/customer/addcustomer.html and reproduce the customer add form in the linked deploy preview using the reported Chrome and Windows environment. Review the name, phone, ID, and email fields; done means the missing format guidance is present and the reported invalid inputs are rejected, with the expected formats confirmed before implementation.

Written by the indexing model from the issue text.